The present invention relates to a steering column of a vehicle having a first and second shaft part which are connected together via a universal-joint-type joint arrangement, which has a first and a second rubber-elastic joint disc, in a manner arranged coaxially with one another in succession as seen in the axial direction and without elastic deformation of the joint discs (within the scope of conventional tolerances). Concerning the state of the art, reference is made to European Patent Document EP 1 080 316 B1.
Elastic joint disks—often also called Hardy disks—are provided in shaft connections for the compensation of tolerances, particularly also with respect to an angle between the longitudinal axes of the shafts to be mutually connected, as well as also for the damping of vibrations of any type, in which case such joint disks may also be used for a decoupling of the two shafts with respect to an undesired vibration transmission.
This explanation basically also applies to the arrangement of elastic joint disks in steering columns of motor vehicles, where, usually by means of a universal joint, two shaft parts are mutually connected—for installation reasons, in the engine compartment of a motor vehicle at an inclination angle—, specifically a first shaft part connected with the driver's steering wheel and a second shaft part connected to a steering gear, from which steering gear, so-called steering tie rods lead to the steerable wheels of the vehicle.
One example of an elastic shaft coupling in a steering column of a motor vehicle is illustrated in the above-mentioned European Patent Document EP 1 080 316 B1, wherein not only one but two elastic joint disks are provided, viewed in the steering column axis direction, arranged quasi behind one another. In this case, these joint disks are arranged inside fittings, which are components of a first or second shaft part—according to the terminology of the present application/invention. The two fittings axially engage in one another with play. The play is dimensioned such that the fittings can be tilted with respect to one another to a limited extent. This should have the purpose of the above-mentioned compensation of tolerances.
By means of the present invention, it was recognized that, while using two elastic joint disks, which are arranged quasi behind one another, in a vehicle steering column but which are installed differently than in the cited prior art, an extremely advantageous additional function can be illustrated that is not shown in this prior art. It is therefore an object of the present invention to provide an advantageous further development of the state of the art.
For a steering column of the type described above, this and other objects are achieved in that an intermediate piece is provided between the two joint disks which is independent of the two shaft parts with respect to its mobility and is connected with the shaft parts by way of the joint disks in the manner of a universal joint such that, in the installed condition of the steering column, in a suitable lateral view, as a result of an elastic deformation of the two joint disks, the axes of rotation of the two shaft parts enclose or form an inclination angle of the steering column.
According to the invention, a universal joint is created by way of two elastic joint disks and an intermediate piece situated in-between. The intermediate piece is connected with the two shaft parts by way of these joint disks toward both sides in each case in a manner of a universal joint, which universal joint simultaneously comprises a vibration-related decoupling function, specifically by way of the elastic joint disks. Simultaneously with the interaction with the single intermediate piece, while elastically deforming, these elastic joint disks form a universal joint, so that pivot bearings or the like otherwise required for typical universal joints will no longer be necessary. It is only required to connect each elastic joint disk, on one side, with its assigned shaft part and, on the other side, in a universal-joint-type manner with the intermediate piece arranged between the two joint disks, whereupon the intermediate piece, while the respective joint disk is elastically deformed, can be moved with respect to the shaft part arranged on the other side of this joint disk, within the scope of the deformation possibility of the respective joint disk.
A universal-joint-type connection between two shafts or the like or, in the present case, by way of a first elastically deformable joint disk, between a first shaft part and the intermediate piece according to the invention or, adjoining the latter, between the intermediate piece by way of the second rubber-elastic joint disk and the/a second shaft part, as known, is characterized in that, in the unbent condition, viewed in the axis direction of one of the shaft parts, in a first plane, which is, for example, horizontal in a certain angle-of-rotation position of the shaft connection, on both sides of the (first) axis of rotation of the shaft and, in this case, slightly spaced away from the latter, a first connection exists (in the present case, between the shaft part and the joint disk), and in that, in a second plane, which is vertical in the example and is generally perpendicular with respect to the first plane, also on both sides of the axis of rotation of the shaft and, in this case, slightly spaced away from the latter, a second connection exists, in the present case, between the joint disk and the intermediate piece according to the invention. Viewed perpendicularly with respect to the quasi common axis of rotation of the shaft, the above-mentioned first connection and the above-mentioned second connection may be situated in a common plane, which, however, is not absolutely necessary. On the contrary, the above-mentioned connections, each viewed perpendicularly with respect to the axis of rotation of the shaft connection, may also be situated in mutually spaced planes, i.e. be arranged behind one another in the rotational axis direction.
In the case of a steering column according to the invention, two so-called “quasi universal joints” are now provided, which are formed by the two rubber-elastic joint disks and are arranged behind one another viewed in the axis direction of the steering column. Specifically, a first “quasi universal joint” is between the first shaft part and the intermediate piece according to the invention, and a second “quasi universal joint” is between the intermediate piece and the second shaft part. For reasons of completeness, it should explicitly be mentioned that, by means of such “quasi universal joints” or such universal-joint-type connections, not only the intermediate piece according to the invention can be moved with respect to the two shaft parts (within the scope of the deformation possibilities of the joint disks) but that, as a result, a mobility of each joint disk limited by the deformation possibilities of the joint disks also exists with respect to the shaft part assigned to it (by way of the universal-joint-type fastening) as well as with respect to the intermediate piece.
A universal-joint-type connection is also contained in the above-mentioned state of the art, but there no intermediate piece is provided between the two shaft parts, which is separated from the latter, or which, within the deformation possibilities of the joint disks, can be moved independently of the shaft parts.
Therefore, while, by means of a steering column according to the invention, in its installed condition in a motor vehicle, an inclination angle of significant magnitude can be illustrated between the two shaft parts, this is not possible in the case of the above-mentioned state of the art. Because of the above-mentioned slight play between the shaft parts mutually engaging in the connection area (there, the so-called “tube pieces”), at best, a slight compensation of tolerances is possible there, but no inclination angle of significant magnitude can be achieved.
In contrast, by means of the present invention, as a result of the two joint disks, which each form a “quasi universal joint”, while the dimensions are conventional, an inclination angle of a magnitude of 20° can be achieved, which is composed of partial inclination angles of approximately 10° respectively in each “quasi universal joint”. Partial inclination angles of this magnitude can be particularly easily shown by means of joint disks essentially conventionally dimensioned for steering columns if the first connections between the joint disk and the respective shaft part, on the one hand, and the second connections between the joint disk and the intermediate piece according to the invention, on the other hand, on different sides of a joint disk and therefore viewed in the axis direction of the steering column or rotational axis direction of the respective shaft part, are spaced away from one another , i.e. provided quasi behind one another.
The arrangement of the two joint disks and of the intermediate piece, which can be moved independently of the shaft parts (within the scope of the deformation possibilities of the joint disks), is specifically such that, viewed in the axis direction of the steering column not installed in the vehicle and therefore without any elastic deformation of the joint disks, the connection between the first shaft part and the first joint disk is established by two connection elements provided in a first plane containing the axis of rotation of the first shaft part on both sides of this axis of rotation. These connection elements preferably extend in the rotational axis direction. The connection between the first joint disk and the intermediate piece is established by two connection elements provided in a second plane perpendicular to the first plane and also containing the rotational axis of the first shaft part, on both sides of this axis of rotation. These connection elements preferably (also) extend in the rotational axis direction. Analogously, the connection between the intermediate piece and the second joint disk can be established by two connection elements provided in a third plane containing the axis of rotation of the second shaft part on both sides of the axis of rotation of the second shaft part. These connection elements preferably extend in the rotational-axis direction of the second shaft part. The connection between the second joint disk and the second shaft part can be established by two connection elements provided in a fourth plane perpendicular with respect to the third plane and containing the axis of rotation of the second shaft part, on both sides of this axis of rotation. These connection elements preferably also extend in the rotational-axis direction.
It becomes clear from this representation that, in the condition in which it is not installed in the vehicle, the steering column does not have any significant inclination angle. The two shaft parts are therefore situated at least coaxially with respect to one another, and the inclination angle occurs only at the steering column installed in the vehicle while the rubber-elastic joint disks are elastically deformed. In this case, the corresponding deformations of each individual joint disk in the form of partial inclination angles add up to a total inclination angle of greater magnitude of the steering column according to the invention. The maximum of the total inclination angle is achieved when, if the steering column is not installed in the vehicle, the first plane mentioned in the preceding paragraph and the third plane mentioned there essentially coincide, i.e. within the scope of conventional tolerances, and the second and the fourth plane essentially coincide, i.e. within the scope of conventional tolerances.
In order to be able to provide the individual above-mentioned partial inclination angles between each joint disk or the assigned shaft part and the intermediate piece according the invention in a collision-free manner, recesses or spacer elements may be provided in or at the intermediate piece but also, or as an alternative, at the joint disks and the shaft parts. Spacer elements (also conceivable in a component-integrated fashion) hold the concerned components sufficiently far apart, while recesses directly avoid a collision.
A particularly advantageous further development of the invention is such that the two joint disks have different designs. With respect to a vibration-related and particularly acoustic decoupling of the two shaft parts from one another, they are or may be designed for different operating ranges and particularly different frequencies or frequency bands. As known, rubber-elastic vibration decoupling elements can be designed for a particularly high effectiveness in a defined frequency band, which can take place, for example, by a suitable selection of material, hardness, forming and more. Because, in the present case, at least two each of such rubber-elastic joint disks are provided, it becomes possible to design the latter in different frequency ranges with respect to a particularly effective decoupling, so that, as a whole, a steering column according to the invention may be designed to be decoupled from vibrations with respect to a particularly broad frequency band, in that the two joint-disk-individual frequency bands are quasi added to one another.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.